Such devices comprise a cylindrical housing with an inlet port leading into an inlet chamber and an exit port for the discharge of the cleaned gas flow. The contaminated gas flow is fed into the inlet chamber which in turn supplies the gas to be cleaned through heat exchanger pipes into a ring combustion chamber. The heat exchanger pipes are arranged cylindrically and axially in the cylindrical housing. These heat exchanger pipes thus form a ring-shaped or cylindrical bundle. The ring combustion chamber encloses at a facing end of the housing a burner which discharges into a flue gas mixing pipe arranged concentrically in the housing. The flue gas mixing pipe in turn leads into a main combustion chamber which passes into a ring chamber leading into the exit port, whereby the cleaned gas flows around the heat exchanger pipe for preheating the gas to be cleaned before it enters into the ring combustion chamber around the burner.
A gas cleaning apparatus as just described requires an external feeding mechanism in the form of a blower for charging the contaminated carrier gas through conduit pipes connected to the inlet chamber of the apparatus. Flaps for controlling the alternative operation with fresh air or for admixing fresh air to the contaminated gas must always be arranged on the suction side of the blower for the contaminated gas. Therefore, these flaps and any mixing devices are to be arranged together with the blower away from the cleaning apparatus. In some instances, the flaps are even arranged further away from the cleaning apparatus than the blower. Frequently, the blower and the additional components for the admixture of fresh air are located in a building while the combustion apparatus for the cleaning of the exhaust gases itself is assembled outside the building.
The alternative operation air, for example, for a start-up operation, for an admixing operation, or for the so-called "stand-by" operation, must always be available. Additionally, such operation air is often required as rather substantial air volumes. Accordingly, if the blower is installed in a building, additional pipe conduits must be installed if the alternative operation air must be sucked in from the outside. Thus, generally, the effort and expense for the installation of the so-called peripheral components of such cleaning plants inside a building is substantial. Available mounting space is required and scaffolds as well as frame structures, must be built, often requiring pipe conduits of substantial length and large cross-section requiring respective heat insulations. Last, but not least, noise insulating measures are unavoidable. The space requirement often encroaches on the actual production systems which in fact must be considered to be more important than the peripheral equipment.
Additionally, these blowers generate a substantial noise which causes a substantial nuisance, because usually these blowers are rather loud high performance blowers. The body noise of such blowers can be insulated with a relatively reasonable effort. However, the air noise caused by these blowers can be kept in permissible limits only with a substantial effort and expense. The conventional, slotted blowout curtains cannot be used in this instance because the slots would be contaminated by the pollutants, by soot, and other materials contained in the carrier gas. Additionally, these co-called blow-out curtains are not capable of withstanding the exhaust gas temperatures. Moreover, the required flexible, that is noise-open connections, on the compression side of the blower, do not permit the use of a so-called slotted blow-out curtain. In view of the foregoing, the entire conventional system, including the combustion plant, and the peripheral components, are altogether very expensive.